1. Field of the Invention
This invention relates to a method of determining the position of the cowl on a longwall shearer by measuring the change in function of apparatus associated with the operation of the ranging arm.
2. Summary of the Prior Art
One system for mining involves a longwall machine commonly called a ranging arm shearer and comprises cutter drums carried on arms pivotally mounted on the machine body. The machine traverses the longwall face of, for example, a coal panel, and deposits the mined material onto a conveyor for transport. Cowls are mounted on the ranging arm to guide the mined material from the cutter onto the conveyor.
As the machine completes the pass of the longwall face and prepares to reverse direction, a headgate or tailgate cutout is performed at which time it is necessary to rotate the cowl from one side of the drum to the other so that the cowl is on the trailing side of the cut. At this sequence of the mining scheme, it is desirable to know the cowl has been moved.
An investigation of the prior art revealed only two patents which appear pertinent. U.S. Pat. No. 4,006,935 teaches a ranging arm shearing machine having sensing means for sensing the position of the rotational axis of a cutter drum mounted on a ranging arm relative to the pivotal axis. U.S. Pat. No. 4,371,209 shows mining machines having ranging drums and sensor means for sensing the position of the axis of the drum and controlling that position in the present cut to duplicate the previous cut.